If you're responding to me, that doesn't seem to be the case. In fact, replacing the stock wings with B9PW actually shaved off a full tonne of mass:
https://imgur.com/a/ocXQo
That's actually including missiles too, so it seems to actually be closer to 1.5 tonnes lighter with B9PWings.

I haven't seen anyone bring it up yet, but the B9 PWings seem to have much less lifting ability compared to the stock wing parts in FAR. Even with identical wing shapes and thickness, aircraft that could maintain energy in a turn now experience heavy stalling with B9 Pwings. I have no idea why that might be.

All my submitted aircraft have updated AI Flight computers and Dynamic Deflection settings as of right now, thoroughly tested against QF-12K!
...Okay that's a little boring, here's something a bit more interesting:
The AV-3W 'Heresy'. An innovative Attack Jet with helicopter handling. Everything just became a runway. https://kerbalx.com/JollyGreenGI/AV-3W-Heresy-KCS

Time for another small batch of planes. Well, not small planes.
The B-4F 'Skyline'. A Mach 2+ strategic bomber with considerable payload and range, carpet bombing never looked so rad: https://kerbalx.com/JollyGreenGI/B-4F-Skyline-KCS
The Nu-65 'Fetch-R'. Propeller driven, gun turrets, this old school strategic bomber has incredible endurance and can literally carry its own weight in ordinance: https://kerbalx.com/JollyGreenGI/Nu-65-Fetch-R-KCS

So I was doing some combat testing against my QF-12K, it turns out the 'Monarch' can outrun AIM-120s, and take a direct hit from a Sidewinder:
Totally necessary I swear, tweaking AI flight computers and dynamic deflection at Mach 2+.